diff --git a/src/types/entities.ts b/src/types/entities.ts
new file mode 100644
index 0000000..53e54e6
--- /dev/null
+++ b/src/types/entities.ts
@@ -0,0 +1,244 @@
+// Lead domain
+export type LeadSource =
+    | 'WEBSITE'
+    | 'FACEBOOK_AD'
+    | 'GOOGLE_AD'
+    | 'INSTAGRAM'
+    | 'GOOGLE_MY_BUSINESS'
+    | 'REFERRAL'
+    | 'WALK_IN'
+    | 'WHATSAPP'
+    | 'PHONE'
+    | 'OTHER';
+
+export type LeadStatus =
+    | 'NEW'
+    | 'CONTACTED'
+    | 'QUALIFIED'
+    | 'NURTURING'
+    | 'APPOINTMENT_SET'
+    | 'CONVERTED'
+    | 'LOST';
+
+export type Priority = 'LOW' | 'NORMAL' | 'HIGH' | 'URGENT';
+
+// Campaign domain
+export type CampaignType =
+    | 'OUTBOUND_CALL'
+    | 'WHATSAPP'
+    | 'SMS'
+    | 'EMAIL'
+    | 'FACEBOOK_AD'
+    | 'GOOGLE_AD'
+    | 'INSTAGRAM_AD';
+
+export type CampaignStatus = 'DRAFT' | 'ACTIVE' | 'PAUSED' | 'COMPLETED';
+
+export type CampaignPlatform = 'FACEBOOK' | 'GOOGLE' | 'INSTAGRAM' | 'YOUTUBE' | 'MANUAL';
+
+// Ad domain
+export type AdStatus = 'DRAFT' | 'ACTIVE' | 'PAUSED' | 'ENDED';
+
+export type AdFormat = 'IMAGE' | 'VIDEO' | 'CAROUSEL' | 'TEXT' | 'LEAD_FORM';
+
+// Activity domain
+export type LeadActivityType =
+    | 'STATUS_CHANGE'
+    | 'CALL_MADE'
+    | 'CALL_RECEIVED'
+    | 'WHATSAPP_SENT'
+    | 'WHATSAPP_RECEIVED'
+    | 'SMS_SENT'
+    | 'EMAIL_SENT'
+    | 'EMAIL_RECEIVED'
+    | 'NOTE_ADDED'
+    | 'ASSIGNED'
+    | 'APPOINTMENT_BOOKED'
+    | 'FOLLOW_UP_CREATED'
+    | 'CONVERTED'
+    | 'MARKED_SPAM'
+    | 'DUPLICATE_DETECTED';
+
+export type Channel = 'PHONE' | 'WHATSAPP' | 'SMS' | 'EMAIL' | 'IN_PERSON' | 'SYSTEM';
+
+export type ActivityOutcome =
+    | 'SUCCESSFUL'
+    | 'NO_ANSWER'
+    | 'BUSY'
+    | 'NOT_INTERESTED'
+    | 'CALLBACK_REQUESTED'
+    | 'INFORMATION_SENT';
+
+// Follow-up domain
+export type FollowUpType = 'CALLBACK' | 'APPOINTMENT_REMINDER' | 'POST_VISIT' | 'MARKETING' | 'REVIEW_REQUEST';
+
+export type FollowUpStatus = 'PENDING' | 'COMPLETED' | 'CANCELLED' | 'OVERDUE';
+
+// Messaging domain
+export type MessageDirection = 'CLINIC_TO_PATIENT' | 'PATIENT_TO_CLINIC';
+
+export type MessageChannel = 'WHATSAPP' | 'SMS' | 'EMAIL' | 'IN_APP';
+
+export type MessageStatus = 'SENT' | 'DELIVERED' | 'READ' | 'FAILED';
+
+export type TemplateApprovalStatus = 'APPROVED' | 'PENDING' | 'REJECTED';
+
+// System
+export type HealthStatus = 'HEALTHY' | 'WARNING' | 'UNHEALTHY';
+
+// Shared sub-types
+type CurrencyAmount = {
+    amountMicros: number;
+    currencyCode: string;
+};
+
+// Entity types
+export type Lead = {
+    id: string;
+    createdAt: string | null;
+    updatedAt: string | null;
+    leadSource: LeadSource | null;
+    leadStatus: LeadStatus | null;
+    priority: Priority | null;
+    contactName: { firstName: string; lastName: string } | null;
+    contactPhone: { number: string; callingCode: string }[] | null;
+    contactEmail: { address: string }[] | null;
+    interestedService: string | null;
+    assignedAgent: string | null;
+    utmSource: string | null;
+    utmMedium: string | null;
+    utmCampaign: string | null;
+    utmContent: string | null;
+    utmTerm: string | null;
+    landingPageUrl: string | null;
+    referrerUrl: string | null;
+    leadScore: number | null;
+    spamScore: number | null;
+    isSpam: boolean | null;
+    isDuplicate: boolean | null;
+    duplicateOfLeadId: string | null;
+    firstContactedAt: string | null;
+    lastContactedAt: string | null;
+    contactAttempts: number | null;
+    convertedAt: string | null;
+    patientId: string | null;
+    campaignId: string | null;
+    adId: string | null;
+};
+
+export type Campaign = {
+    id: string;
+    createdAt: string | null;
+    updatedAt: string | null;
+    campaignName: string | null;
+    campaignType: CampaignType | null;
+    campaignStatus: CampaignStatus | null;
+    platform: CampaignPlatform | null;
+    startDate: string | null;
+    endDate: string | null;
+    budget: CurrencyAmount | null;
+    amountSpent: CurrencyAmount | null;
+    impressionCount: number | null;
+    clickCount: number | null;
+    targetCount: number | null;
+    contactedCount: number | null;
+    convertedCount: number | null;
+    leadCount: number | null;
+    externalCampaignId: string | null;
+    platformUrl: string | null;
+};
+
+export type Ad = {
+    id: string;
+    createdAt: string | null;
+    updatedAt: string | null;
+    adName: string | null;
+    externalAdId: string | null;
+    adStatus: AdStatus | null;
+    adFormat: AdFormat | null;
+    headline: string | null;
+    adDescription: string | null;
+    destinationUrl: string | null;
+    previewUrl: string | null;
+    impressions: number | null;
+    clicks: number | null;
+    conversions: number | null;
+    spend: CurrencyAmount | null;
+    campaignId: string | null;
+};
+
+export type LeadActivity = {
+    id: string;
+    createdAt: string | null;
+    activityType: LeadActivityType | null;
+    summary: string | null;
+    occurredAt: string | null;
+    performedBy: string | null;
+    previousValue: string | null;
+    newValue: string | null;
+    channel: Channel | null;
+    durationSeconds: number | null;
+    outcome: ActivityOutcome | null;
+    leadId: string | null;
+};
+
+export type FollowUp = {
+    id: string;
+    createdAt: string | null;
+    followUpType: FollowUpType | null;
+    followUpStatus: FollowUpStatus | null;
+    scheduledAt: string | null;
+    completedAt: string | null;
+    priority: Priority | null;
+    assignedAgent: string | null;
+    patientId: string | null;
+    callId: string | null;
+    // Denormalized fields
+    patientName?: string;
+    patientPhone?: string;
+    description?: string;
+};
+
+export type PatientMessage = {
+    id: string;
+    createdAt: string | null;
+    subject: string | null;
+    body: string | null;
+    direction: MessageDirection | null;
+    channel: MessageChannel | null;
+    priority: Priority | null;
+    sentAt: string | null;
+    readAt: string | null;
+    senderName: string | null;
+    patientId: string | null;
+    // Optional fields
+    status?: MessageStatus;
+    recipientName?: string;
+    recipientPhone?: string;
+};
+
+export type WhatsAppTemplate = {
+    id: string;
+    name: string | null;
+    body: string | null;
+    variables: string[];
+    linkedCampaignId: string | null;
+    linkedCampaignName: string | null;
+    approvalStatus: TemplateApprovalStatus | null;
+    language: string[];
+    sendCount: number | null;
+    deliveredCount: number | null;
+    readCount: number | null;
+    clickedCount: number | null;
+    failedCount: number | null;
+};
+
+export type Agent = {
+    id: string;
+    name: string | null;
+    initials: string | null;
+    isOnShift: boolean | null;
+    shiftNote: string | null;
+    avgResponseHours: number | null;
+    activeLeadCount: number | null;
+};